Manufacture of triple superphosphate



United States Patent 3 389 959 MANUFACTURE OF rmiu: SUPERPHOSPHATE Donald E. Lee, Atlanta, Ga., assignor, by mesne assignments, to Armour Agricultural Chemical Company, a

The oven heating step may be for any suitable period but ordinarily 30 minutes is a sufficient time for such heating.

Specific examples illustrative of the process maybe set out as follows:

cor oration of Delaware No Drawing. Filed Apr. 30, 1965, Ser. No. 452,347 EXAMPLE I 3 Claims- A low grade phosphate rock (61.4 BPL), which heretofore has been considered unsuitable for triple superphosphate production, was mixed with 65 weight percent P 0 ABSTRACT OF THE DISCLOSURE wet rrocess superphosphoric acid. The phosphate rock Triple superphosphate is prepared by acidulating lowwas mm Bartow Fla-4 and contamed grade phosphate ore having less than 62 BPL wi h wet CaO, 28. 10% P O and 3.40% fluorine. The wet process superphosphoric acid having at least 65 weight perphosphqnc 1d had a total P205 of 720% an cent P 0 equivalent and at a P O /CaO ratio of about ortho, phosphonc and content of 385% P205 and a 1.0 to 1.1, and heating the mixture to a temperature in 15 fiuonne confent of 1 the range of about 25045? F, and storing the heated The reaction cond1t1ons are set out as follows: mass for reaction to form triple superphosphate. While the o superphosphoric acid may be mixed with the phosphate lmtlalTemp" rock at room temperatures, the superphosphoric acid is No.1 No.2 No.3 preferably heated to about 250450 F. and then mixed 20 Rock Room 100 110 with the rock and the mixture then heated to 250450 F. Acid 150 7 180 before being stored in a den for reaction to form triple set Time,sec superphosphate. Den 50 37 40 o I I a This invention relates to the manufacture of triple super- The product analysls is set out m the followmg table phosphate and more particularly to the beneficiation of TABLEI low grade phosphate rock or ore through the production No.1 No.2 No.3

rocess. p An object of the invention is to provide for the pro- 1 25323Ethaner;o;::::::::::::::::::: 4533" G13 4 11? duction of triple superphosphate from low grade phosphate "I 3 2 3:3 8:2 rock WhlCh has heretofore been considered unsuitable for Percent Water Soluble P20 40.1 45.1 45.3 triple superphosphate production. Another object is to gfgggggl if; 3% 6 provide a process in which superphosphonc aClCl 1s em- Percent Available of Total P2 90.5 95.1 93.9 ployed effectively for the benefieiation of low grade phos- Percent cmversm P205 8&9 phate ore or rock and to produce triple superphosphate of substantially greater than 46% P 0 analysis. Yet another EXAMPLE H object is to provide a process employing effective Superphosphoric acid was heated in 100 ml. beakers on P O /CaO ratios and initial heating steps by which triple a hotplate to 300 F. The acid had a total of 71.05 weight superphosphate is produced having a relatively high P 0 percent of P 0 43.3% ortho and 0.17% insoluble P 0 analysis from low grade phosphate of less than 62 BPL. The hot acid was mixed with low grade phosphate rock Other'specific objects and advantages will appear as the at a P O /CaO ratio of 1.0. The rock was Bartow, Fla. specification proceeds. phosphate rock having 0.1% H 0, 40.15% CaO, 28.1%

In one embodiment of the invention a low grade phOS- P 0 and 3.4% fluorine. phate rock of less than 62 BPL is treated with wet Three sets of the above samples were placed in ovens process superphosphoric acid having at least 65% P 0 regulated to the following temperatures: 431 F., 345 F. weight percent and thereafter the mixture is stored in a and 277 F. After being heated for 30 minutes at the den, as in a conventional triple superphosphate process, above temperatures, the samples were stored for nine days for reaction to form a triple superphosphate product. in the conventional triple superphosphate den for further In the foregoing process, I employ a P O /CaO ratio of reaction and at the end of nine days the triple superphos- 0.9 to 1.1, the ratio of 1.0 or 1.1 being preferred. While phate products analyzed as follows:

TABLE II Temp,, Percent P205 Percent Free Percent Avail Percent Cone Percent F. Acid able of Total version of Rock Total C. I. Avail. Water Sol. P105 P205 the mixing operation may be carried on at room tempera- While in the foregoing specification I have set forth ture, I prefer to heat the superphosphoric acid to temperaspecific embodiments of the invention in considerable detures above 100 F. and preferably to the temperature tail for the purpose of illustrating the invention, it will range of 250-450" F. If desired, the superphosphoric acid be understood that such details may be varied widely may be preliminarily heated to about 300 F. and low by those skilled in the art without departing from the grade phosphate rock may be mixed with the hot acid spirit of my invention. preferably at a P O /CaO ratio of 1.0. Thereafter, the Iclaim: mixture may be heated, as by placing in ovens, to the 1. In a process for the manufacture of triple superhigher range of temperatures preferably 250-450 F. and phosphate, the steps of acidulating low-grade phosphate the heated mixture then stored in a den, say for about ore having less than 62 BPL, with wet process supernine days, etc., to produce the triple superphosphate product.

phosphoric acid having at least 65 weight percent P 0 equivalent and at a P O /CaO ratio of about 1.0 to 1.1,

heating the same to a temperature in the range of about 250-450 F. and storing the heated mass for reaction to form triple superphosphate.

2. In a process for the manufacture of triple superphosphate, the steps of acidulating low-grade phosphate ore having a BPL less than 62 with wet process superphosphoric acid having in excess of 70 weight percent P 0 equivalent and at a P O /CaO ratio of about 1.0, heating the same to a temperature in the range of 250450 F. and storing the heated mass for reaction to form triple superphosphate.

3. In a process for the manufacture of triple superphosphate from low grade phosphate rock, the steps of mixing phosphate rock having a BPL below 62, With wet process superphosphoric acid of about 72 weight percent P 0 equivalentand a P O /CaO ratio of about 1.0, heating the mixture to a temperature of about 25 0- 450 F. fora period of about 30 minutes, and then storing the heated mass in a den for reaction to form triple superphosphate.

References Cited UNITED STATES PATENTS Knox 2 3 109 Carpenter et a1; 23 109 Block 23%1 09 Block 23-109 Bridger 7l-'-41 Baumann 71 34 

